Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Maskey M.L., Al-Sudani A., Nelson A.M., Quintana Ashwell N.

The Mississippi Delta is one of the largest contiguous agricultural production areas in the United States. Overlying an alluvial plain, this area is known for producing row crops such as cotton, soybeans, and corn, as well as rice and catfish. Therefore, this region is a major economic contributor to the state and nation, with $6.8 billion in annual agriculture revenue. The Delta receives over 54 inches of rain annually, but most of that precipitation occurs outside the growing season. Consequently, the region depends on irrigation to sustain agricultural production in the state largely depends on. Over time, the number of wells has expanded to meet abundant and accessible water of sufficient quality for the ever-increasing expansion of irrigated acreage. According to the Mississippi Department of Environmental Quality, the number of permitted wells increased from 10,571 to 21,000 between 2000 and 2022. As a result, groundwater levels in the shallow Mississippi River Valley aquifer have declined. However, data gaps make it difficult to interpret water conditions in this alluvial aquifer, which limits the ability to make realistic recommendations. Therefore, we propose a protocol to develop a coupled groundwater model that incorporates hydrologic dynamics and economic behavior in the presence of surface water sources. Therefore, we propose a protocol to develop a coupled groundwater model that incorporates hydrologic dynamics and economic behavior in the presence of surface water sources. This protocol addresses different agricultural management practices to study groundwater and surface water interactions. Additionally, the integrated groundwater model will be used to optimize water delivery costs, crop yields, and extraction from existing wells. We propose an economic modeling tool widely used in policy analysis: "Positive Mathematical Programming," that replicates observed economic behavior under alternative hydroeconomic circumstances. At this stage, we present a conceptual framework to develop the integrated modeling platform with the available data. We also plan to extend this study by generating historical and future plausible scenarios that will inform decision-makers about viable strategies to address groundwater concerns in the Delta. We envision that this research will serve as a multi-benefit protocol in a) generating timeseries of groundwater data from the past to the future, to understand subsurface dynamics; b) optimizing groundwater well extraction levels under different land use, agriculture management practices and climate conditions; and c) informing feasible water delivery costs, crop yields, and groundwater withdrawal under sustainable aquifer conditions.